The present invention refers to a device for introducing soft short catheter-cannulas into a blood-vessel by means of a puncturing member for puncturing the blood-vessel, a connection member being arranged at the rear end of the catheter-cannula remote from the blood-vessel as seen during its use.
Plastic catheter-cannula inserted into a blood-vessel are used to a great extent for sampling of blood and administration of drugs, fluid and blood. They have the advantage over steel needles because they do not easily cause vessel and tissue injuries and haematoma formation when the patient moves.
A serious side-effect of plastic catheter-cannulas, however, is the high incidence of thrombosis and thrombophlebitis.
Thrombosis induced by contact with blood of plastic surfaces is a major unsolved problem and a great number of factors are probably involved. It has been repeated however that soft catheter-cannulas, especially those made of silicone elastomers are less thrombogenic than catheter-cannulas made of a stiffer material, e.g. PVC, polyethylene, Teflon.sup.R.
These soft catheter-cannulas are however very difficult to insert into a blood-vessel as they easily bend and get twisted.
In order to facilitate vascular insertion of long, soft catheter-cannulas a number of methods are proposed, which however are not adapted for short catheter-cannulas, owing to the limitation on one hand are traumatic for small, peripheral veins and arteries and on the other hand they are expensive and cumbersome.
Among these methods can be mentioned the use of stiff introducer-cannulas made of, for example Teflon.sup.R, surgical methods, use of a steel winged needle through which the catheter-cannula is inserted and which splits longitudinally when it is removed from the vessel.
In the European patent application No. 0.021.446 there is described an introducer-cannula of stiff plastic provided with longitudinal lines of weakness and intended for the insertion of long catheter-cannulas in a blood-vessel. After insertion of the catheter-cannula the introducer-cannula is withdrawn and removed from the catheter-cannula by severing its two halves along the lines of weakness. This device is however only adapted for long catheter-cannulas and not for the insertion of soft, short catheter-cannulas into veins and arteries.
There is however a method presently in use and adapted for insertion of short, soft catheter-cannulas. The method is developed by VICRA, a division of Travenol Laboratories, USA. The device used comprises a longitudinally slotted needle which permits the insertion of a 5 cm long silicone elastomer catheter-cannula armoured with a metal spring stylet. After insertion of the catheter-cannula the needle and the stylet are withdrawn.
Both device and method are however not without problem. Vein puncture is difficult and traumatic because of the slotted needle which has a diameter significantly larger than that of the silicone eleastomer catheter-cannula, withdrawal of the metal spring stylet may sometimes be difficult and the device may be expensive.
In the European patent application No. 0.002.607 there is described a device for implanting a pacemaker electrode through the subclavion vein into the heart. The device comprises an introducer sleeve arranged on the outside of the needle and provided with a longitudinal line of weakness along which the introducer sleeve can be severed and removed from the body when the electrode has been placed in the desired position.
The device is adapted for insertion of long, rigid implants (pacemaker electrodes) through the subclavion vein and is not adapted for insertion of soft, short catheter-cannulas into peripheral veins and arteries.